a. Field of the Invention
The present invention relates generally to a method and system for generating a surface model of a geometric shape. More particularly, the present invention relates to a computer-implemented method and system for generating a surface model of an anatomic structure, such as the heart, or a particular portion thereof, using surface point data.
b. Background Art
For many years, computer-implemented methods and systems have been used to generate surface models of geometric shapes including, for example, anatomic structures. More specifically, a variety of methods or techniques have been used to generate surface models of the heart and/or particular portions thereof (e.g., the heart as a whole or particular structures and/or portions thereof).
In one particular method, a plurality of sample points are taken on the surface of the structure being modeled that correspond to the relative location of the structure at that particular point. A surface model of the structure is then constructed based on the convex hull of the collection of sample points. In general terms, to collect the sample points, the surface of the structure is swept with a catheter and the various points on the surface of the structure visited by the catheter are recorded using known methods. These individual points collectively form a cloud of points (See, for example, FIG. 4). The convex hull of the cloud of points is then computed using known convex hull algorithms (See, for example, FIG. 5). The resulting convex hull shape estimates the boundary of the structure from the set of points, and therefore, provides a surface model of the structure. An advantage of this type of method/technique is that areas of the modeled structure that are not visited by the catheter, either because the catheter cannot reach the particular area or the clinician taking the samples did not collect samples from that area, are “filled in” during the model construction phase to create a complete model.
This advantage, however, may also be the principal disadvantage of these methods/techniques. For instance, because areas of the structure are “filled in”, these techniques cannot reconstruct features of the modeled structure that are concave. Accordingly, with respect to the modeling of the heart, for example, these techniques cannot reconstruct certain anatomic features within the heart, such as papillary muscles or pulmonary vein ostia, which are both concave structures that would normally “indent” the heart surface model. Thus, while these techniques provide a good generalized model of the structure, they do not provide the level of detail that would be useful for many different applications.
Accordingly, there is a need for a method and system of generating surface models, such as, for example, cardiac surface models, that will minimize and/or eliminate one or more of the above-identified deficiencies.